Percutaneously deliverable intravascular filter prosthesis

ABSTRACT

An intravascular prosthesis comprises a lining rolled upon itself around an axis so that it is introducible into a vascular lumen. An inflatable channel is included for unrolling the lining when the prosthesis is positioned within the lumen so that the lining may engage the vascular wall to provide support therefor. A filter is provided for filtering the blood which passes through the prosthesis when the lining is unrolled.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an intravascular prosthesis, and moreparticularly, concerns a percutaneously deliverable prosthesis suitablefor the intravascular filtration of blood so that migration of bloodclot emboli may be prevented.

2. Description of the Prior Art

Blood vessels of humans or animals undergo a natural degenerativeprocess or are sometimes subject to weakness. In weakened blood vessels,aneurysms may occur. The degenerative effect on blood vessels may alsocause a narrowing or constriction of the lumen of the vessel so thatblood flow is restricted. In other degenerative situations, or for otherreasons, clots or emboli may occur which, should they migrate within theintravascular system, could be very dangerous.

With respect to the aforementioned intravascular problems, surgicalintervention has been the primary technique for providing relief. Forexample, aneurysm repair involves a surgical procedure in which anintraluminal vascular prosthesis is inserted into the damaged vessel toreconstruct the section that needs repair. For clogged blood vessels,the excision of thickened atheromatous areas of the vessel has beenperformed by an endarterectomy procedure. Vascular filter, such as thoseplaced in the vena cava, presently involves the positioning of aexpandable structure or balloon within the vena cava. Such filters havebeen known to migrate, and are often difficult to properly orient withinthe vena cava. These and other intravascular therapy procedures of aninvasive nature are not only risky, but are also costly.

Angioplasty procedures, using expandable balloons, have been developedfor widening the lumen of diseased, constructed blood vessels. Many ofthese angioplasty procedures are performed percutaneously so that theballoon is introduced into the blood vessel through a catheter insertedthrough the skin into the vascular system. After the inflation of theexpandable balloon widens the clogged blood vessel, it is withdrawn fromthe blood vessel through the introducer catheter. Balloon catheters arealso available in which the inflated balloon is detachable from thecatheter once inflated within the blood vessel. The inflated, detachedballoon occludes the blood vessel, and is therefore useful in suchprocedures as varicocele treatment. Such a detachable balloon cathetersystem, known as the MINIBALLOON™ catheter, is sold by Becton, Dickinsonand Company, Paramus, N.J.

Although inflatable and detachable balloon catheter procedures,performed percutaneously, are known and available for some intravasculartherapy applications, surgery is still relied upon for otherapplications. Less invasive techniques are being sought for blood vesselrepair, reconstruction and filtering, as well as vessel occlusion, bloodflow regulation or flow assist. The present invention is directed to adevice which provides for minimal invasive methods of intravasculartherapy. In particular, the present invention is directed to anintravascular prosthesis, percutaneously deliverable, which is suitablefor the filtration of blood clot emboli in the blood and for thereinforcement or reconstruction of weakened blood vessels, as well asaneurysm repair. Two copending patent applications, having a commonassignee herewith, Ser. No. 772,216 and Ser. No. 772,217 both filed onSept. 3, 1985 relate to those intravascular therapy applicationsinvolving blood vessel reinforcement without filtering, and to bloodvessel occlusion and blood flow regulation.

SUMMARY OF THE INVENTION

The intravascular prosthesis of the present invention comprises a liningrolled upon itself around an axis so that it is introducible into avascular lumen. Means, associated with the lining, are provided forunrolling the lining when the prosthesis is positioned within the lumenso that the lining may engage the vascular wall to provide supporttherefor. Filter means are included to filter the blood which passesthrough the prosthesis when the lining is unrolled.

In a preferred embodiment of this aspect of the invention, an inflatablechannel is associated with the lining and is rolled upon itself aroundthe same longitudinal axis around which the lining is rolled. Thechannel includes a filling port for the introduction of fluid into thechannel for inflation. The lining and the channel have the capability ofunrolling when the channel is inflated so that the lining may engage thevascular wall. A porous filter, such as a flexible, reticulated member,is connected to the lining. The filter is positioned so that, when thelining is unrolled, the filter extends substantially transversely acrossthe interior of the unrolled lining. Blood clots, atheromatous debris orother emboli are thus prevented from passing through the prosthesis.

Another aspect of the present invention is an intravascular prosthesisassembly which includes a lining, means for unrolling and filter means,as described above, and activation means connected to the means forunrolling for causing the lining to unroll.

A further aspect of the present invention is an intravascular prosthesiskit comprising a prosthesis, as described above, and activation meansfor connection to the means for unrolling for causing the lining tounroll.

In accordance with the principles of the present invention, theintravascular prosthesis hereof has significant advantages over knowndevices for intravascular therapy, almost all of which require surgicalintervention. The present prosthesis may be delivered to, positioned anddetached in, or withdrawn from a blood vessel through a percutaneouscatheter or cannula. As a result, the present prosthesis obviates costlyand risky surgery, and allows for a quick, simple and least invasivemethod of vascular filtration. Placement of the prosthesis of thepresent invention may be performed under fluoroscopic visualization and,perhaps, under local anesthesia. In certain aspects of the presentinvention, the unrolling feature may be reversed so that the prosthesismay be removed from the blood vessel, or even replaced should suchreplacement be required. In other instances, the lining of theprosthesis may be seeded with cells, such as endothelial cells, orotherwise treated to enhance and facilitate the features of theinvention and to prevent blood clots from forming. Since the prosthesisof the present invention may be designed to be detachable, it may beleft in the blood vessel as a permanent implant. This prosthesis hasspecific application to vena cava filtering, but may also have otherblood filtering applications, such as the prevention of intracranialemboli in those patients who experience transient ischemis attacks orare otherwise susceptible to stroke. It can be seen that the versatilityof the present invention provides for many different intravasculartherapy applications.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the preferred embodiment of theintravascular prosthesis of the present invention illustrated in itsnormal, rolled condition;

FIG. 2 is a perspective view of the preferred embodiment of theintravascular prosthesis illustrated in the unrolled, inflated conditionas it may appear when engaged against the vascular wall;

FIG. 3 is a cross-sectional view of a blood vessel illustrating thepositioning of the introducer catheter for the delivery of theintravascular prosthesis into the blood vessel;

FIG. 4 is an end view of the blood vessel illustrated in FIG. 3;

FIG. 5 is a cross-sectional view of the blood vessel illustrating thedelivery of the intravascular prosthesis in its normal, rolledcondition;

FIG. 6 is an end view of the blood vessel and intravascular prosthesisillustrated in FIG. 5;

FIG. 7 is an enlarged cross-sectional view of the connection between theintravascular prosthesis and the catheter for providing fluid to theprosthesis;

FIG. 8 is an enlarged cross-sectional view of the filling port of theprosthesis illustrating its fluid-tight closure after the fillingcatheter has been removed;

FIGS. 9a-9e are end views of the intravascular prosthesis inside theblood vessel illustrating the sequential unrolling of the prosthesisuntil it engages the vascular wall of the blood vessel;

FIG. 10 is a cross-sectional view of the blood vessel illustrating theintravascular prosthesis in the unrolled condition engaging theintravascular wall;

FIG. 11 is an end view of the blood vessel and intravascular prosthesisillustrated in FIG. 10;

FIG. 12 is a cross-sectional view of the blood vessel illustrating theintravascular prosthesis implanted in the blood vessel after theintroducer catheter and the filling catheter have been removed; and

FIG. 13 is an end view of the blood vessel and the intravascularprosthesis illustrated in FIG. 12.

DETAILED DESCRIPTION

While this invention is satisfied by embodiments in many differentforms, there is shown in the drawings and will herein be described indetail a preferred embodiment of the invention, with the understandingthat the present disclosure is to be considered as exemplary of theprinciples of the invention and is not intended to limit the inventionto the embodiment illustrated. The scope of the invention will bemeasured by the appended claims and their equivalents.

Adverting now to the drawings, and FIG. 1 in particular, there isillustrated the preferred intravascular prosthesis 20 of the presentinvention as it appears in the normal, relaxed condition. Prosthesis 20includes a segment of a lining material 21 which is preferably flexiblein nature. Lining 21 is rilled upon itself around a longitudinal axis 22so that a cylinder is formed. For purposes of the present invention, theterm "rolled upon itself" regarding the lining not only includesrolling, but also covers folding, wrapping, gathering or the like of thelining so that the lining may be reduced in size and then subsequentlyexpanded or opened-up to carry out the functions contemplated by thepresent invention. The number of turns or rolls of lining 21 is normallynot important to the present invention, except that a relativelytightened or small diameter roll is more amenable to entering bloodvessels having a small vascular lumen. The length of lining 21 may varyaccording to the intended purpose of the invention. It is also desirablethat, once rolled, lining 21 remain in the rolled condition until theprosthesis has been positioned within the blood vessel.

Once positioned in the blood vessel as will be more completely describedhereinafter, radial expansion of the prosthesis is to be achieved. Suchexpansion occurs by the unrolling of lining 21. To facilitate thisunrolling, one or more inflation channels are provided to unroll lining21. In FIG. 2, which illustrates prosthesis 20 in the unrolledcondition, four such inflation channels 24 are provided. It isunderstood that the number of such inflation channels may vary accordingto many factors including the desired support to be provided by theprosthesis, the length of the prosthesis, the opening of the vascularlumen, etc. Each inflation channel 24 is preferably a tubular band ofmaterial circumferentially oriented around longitudinal axis 22 as wellas around lining 21. Inflation channels 24 are preferably connected tolining 21 so that the axial spacing between each channel may bemaintained and so that stability of the prosthesis may occur.Interconnecting inflation channels is a conduit 25 which is in fluidcommunication with each of the inflation channels. A filling port 26,also in fluid communication with inflation channels 24 and conduit 25,is provided so that fluid may be introduced to the interior of theinflation channels. The details of filling port 26 will be describedmore fully hereinafter.

In the normal, relaxed condition, inflation channels 24 are also rolledupon themselves around longitudinal axis 22 so that the rolledprosthesis appears as illustrated in FIG. 1. Upon the introduction offluid into inflation channels 24, they expand causing their ownunrolling as well as the unrolling of lining 21 so that, upon fullinflation, prosthesis 20 appears as illustrated in FIG. 2. In theunrolled condition the inflation channels and lining define an openinterior passageway 27 along longitudinal axis 22 so that blood mayfreely pass through the prosthesis. Although not necessary for everyapplication of the present invention, there may be circumstances whenthe present invention is not intended for a permanent implant, orperhaps, the hemodynamics related to the prosthesis dictate that it beremoved from the blood vessel. In such circumstances, it is preferredthat inflation channels 24, as well as lining 21, have the capability ofreturning to the rolled condition after inflation of the channels.Having such a memory capability, whereby the unrolling of the prosthesisis reversed, permits the prosthesis to be removed or retrieved from theblood vessel should physiological conditions so warrant.

As seen in FIG. 2, prosthesis 20 includes two filters 28 spaced apartfrom each other along longitudinal axis 22. These filters are preferablyflexible, open-mesh or reticulated screens having pores 29 therethroughso that blood may pass through the filters. However, the filters serveto catch blood clot emboli which may be present in the blood flow andprevent the migration of the emboli to other parts of the vascularsystem. A suitable pore rating is selected for the filters to achievesuch emboli-catching function. The filters should also have sufficientflexibility so that they may be folded within the rolled prosthesis.Although two filters are herein described, it is understood that onesuch filter, or more than two, could be employed for the presentinvention. Each filter 28 may be connected to the lining or aninflatable channel by adhesives, thermoplastic welding or othercompatible technique.

Insofar as the prosthesis of the present invention is intended forintravascular use, it is preferred that all materials for the prosthesisbe biocompatible. Inflation channels 24, lining 21 and filter 28 may beformed of flexible, polymeric material such as silicone, polyurethane orthe like. In order to protect against the formation of a thrombosis, itmay be desirable, especially when used in smaller bore vessels, to treator seed lining 21 with cells to increase duration of patency. Forexample, lining 21 may be seeded with human endothelial cells inasmuchas these cells line the walls of blood vessels. Further, prosthesis 20may be treated with heparin, other anti-clotting agents, plasma surfacemodification or the like to prevent blood clots from forming in theblood after the prosthesis is positioned in the vascular lumen.

Turning now to FIGS. 3 and 4, a blood vessel 30 is schematicallyillustrated within the body 31 of an animal or human. The skin of thepatient has been pierced, as well as blood vessel 30, and a hollowintroducer catheter 34 has been percutaneously positioned within thelumen of the blood vessel. Introducer catheter 34 serves primarily as aguide to introduce the intravascular prosthesis to the affected sitewithin the blood vessel.

Delivery and positioning of intravascular prosthesis 20, in the rolledcondition, is illustrated in FIGS. 5 and 6. It can be seen thatprosthesis 20 is connected, by virtue of its filling port 26, to acatheter 35. It is preferred that catheter 35 be flexible and hollow sothat it may deliver fluid from outside of the patient's body toinflation channels 24 in the intravascular prosthesis. The end offlexible catheter 35 outside of the patient may be connected to a fluidsource (not shown) so that fluid may be delivered, preferably, underpressure, to the prosthesis inside the blood vessel.

Reference is made to FIGS. 7 and 8 which illustrate the connection ofcatheter 35 to prosthesis 20, as well as the detachment of theprosthesis from the catheter. A valve 36 is included within filling port26 of the prosthesis so that fluid may enter the inflation channels yetremain there without escaping after detachment of prosthesis 20 fromtethering and filling catheter 35. In the embodiment illustrated inFIGS. 7 and 8, valve 36 is a duck-bill valve, although other embodimentsof such a valve may be employed. Once prosthesis 20 has been unrolleddue to the inflation pressure of the inflation channels, catheter 35 maybe slipped out of filling port 26 and valve 36 whereby the valve closesand the fluid remains inside the prosthesis. The choice of fluids toinflate the inflation channels may include saline solution, an osmoticfilling agent having an osomosis level to substantially balance theosmotic level of blood, or the fluid may include a hardening agent sothat the prosthesis may be left as a permanent implant inside the bloodvessel.

FIGS. 9a-9e graphically represent the sequential unrolling ofintravascular prosthesis 20 inside blood vessel 30. In FIG. 9a,prosthesis 20 has been introduced into blood vessel 30 in the rolledcondition. FIG. 9a is essentially an enlarged view of FIG. 6. As fluidis introduced into inflation channels 24, the fluid actuates anunrolling and expansion process, the intial stage of which isillustrated in FIG. 9b. FIGS. 9c and 9d represent further filling ofinflation channels 24, with the inflation channels taking on a loop-likeconfiguration. FIG. 9c further illustrates that filling port 26 hasstarted to move toward the intravascular wall as the loop is beingformed. The closeness of filling port 26 to the intravascular wall ofblood vessel 30 is more clearly highlighted in FIG. 9d. Upon fullinflation of inflation channels 24, the prosthesis engages the vascularwall as illustrated in FIG. 9e. Inasmuch as the prosthesis has beencompletely unrolled, interior passageway 27 is thereby formed alonglongitudinal axis 22 (as seen in FIG. 2) which permits blood to passthrough the prosthesis. Filter 28 is also illustrated extendingsubstantially transversely across the interior of the unrolledprosthesis so that it may prevent blood clots from passing through theprosthesis.

FIGS. 10 and 11 depict the unrolled prosthesis 20 engaging the wall ofblood vessel 30. Catheter 35 which cooperates to activate the unrollingof the prosthesis by delivering fluid thereto is still connected tofilling port 26. The expansion of prosthesis 20 due to inflationprovides reinforcement and support of the blood vessel to which it isengaged. The radial expansion of the prosthesis produces a fixationeffect within the blood vessel and permits filling catheter 35 to bewithdrawn from filling port 26. The permanency of the fixation effect,as described above, is achieved by either or both of the followingmeans: the valve in the filling port of the prosthesis serves to preventthe escape of fluid from the inflation channels of the prosthesis, orthe prosthesis may be filled with a solidifying fluid as the final stepbefore detachment of the catheter. If prosthesis 20 is merely fortemporary purposes or because of physiological conditions should notremain within blood vessel 30, fluid inside the inflation channels maybe withdrawn through filling catheter 35 whereupon prosthesis 20 revertsto its rolled condition. This reversibility feature will allow theremoval or retrieval of prosthesis 20, if necessary or desired.

FIGS. 12 and 13, on the other hand, illustrate prosthesis 20 as adetached, permanent implant within blood vessel 30. Support andreinforcement are provided by the prosthesis which engages the vascularwalls. Further, blood may freely flow through passageway 27 which isformed after the prosthesis has been unrolled, but blood clot emboli inthe blood will be trapped by the mesh of filters 28.

Although it is preferred that filling catheter 35 be connected tofilling port 26 of the prosthesis during initial assembly of theprosthesis, these components may be assembled just prior to use of thedevice. In this regard, a kit may be provided which includes theintravascular prosthesis, comprised of the lining, inflation channelsand at least one filter, an introducer catheter and a filling catheter,along with other components which may facilitate the use of the devicein a blood vessel.

Thus, the present invention provides a percutaneously deliverableintravascular prosthesis. The present invention is suitable for variousintravascular therapy applications and is particularly useful forfiltration of blood to prevent the migration of emboli. Such filtrationmay be achieved using the prosthesis of the present invention withminimal invasion of the patient's body thereby achieving a conservativeapproach for such medical procedures.

What is claimed is:
 1. An intravascular prosthesis comprising:a liningrolled upon itself in a plurality of turns around a longitudinal axis sothat it is introducible into a vascular lumen surrounded by a vascularwall; an inflatable channel associated with said lining and being rolledupon itself around said longitudinal axis, said channel including afilling port for the introduction of fluid into said channel for theinflation thereof, said lining and said channel having the capability ofunrolling when said channel is inflated so that the lining may engagethe vascular wall to provide support therefor; and a porous filterconnected to said lining and positioned so that, when the lining isunrolled, said filter extends substantially transversely across theinterior of said unrolled lining to prevent blood from passing throughthe prosthesis.
 2. The prosthesis of claim 1 wherein the unrolled liningand channel, when the channel is inflated, defines an intravascularprosthesis having an open interior passageway along said longitudinalaxis so that blood may pass therethrough, with said filter extendingacross said passageway to prevent blodo clots from passing therethrough.3. The prosthesis of claim 1 wherein there is a plurality of rolled,inflatable channels associated with said lining and spaced axially fromeach other along said longitudinal axis.
 4. The prosthesis of claim 3wherein said inflatable channels are interconnected by a fluid conduitin fluid communication with said filling port so that all of saidchannels may be inflated.
 5. The prosthesis of claim 1 wherein saidfilter is flexible.
 6. The prosthesis of claim 5 wherein said filter isreticulated.
 7. The prosthesis of claim 1 wherein there is a pluralityof said filters spaced axially from each other along said longitudinalaxis.
 8. The prosthesis of claim 1 wherein said prosthesis is made ofbiocompatible material.
 9. The prosthesis of claim 8 wherein said liningis seeded with endothelial cells.
 10. The prosthesis of claim 8 whereinsaid prosthesis is treated to prevent blood clots from forming in theblood after said prosthesis is positioned in the vascular lumen.
 11. Theprosthesis of claim 1 wherein said lining and said channel have thecapability of returning to the rolled condition after inflation of saidchannel.
 12. The prosthesis of claim 1 which further includes a valveassociated with said filling port so that fluid introduced into saidchannel is prevented from escaping thereby maintaining said channel inan inflated condition.
 13. An intravascular prosthesis comprising:alining rolled upon itself in a plurality of turns around an axis so thatit is introducible into a vascular lumen surrounded by a vascular wall;means for unrolling the lining when the prosthesis is positioned withinsaid lumen so that the lining may engage the vascular wall to providesupport therefor, said means for unrolling further including actuationmeans for causing said lining to unroll, said actuation means beingfluid introduced into said means for unrolling; and filter means forfiltering the blood which passes through the prosthesis when said liningis unrolled.
 14. An intravascular prosthesis assembly comprising:alining rolled upon itself in a plurality of turns around an axis so thatit is introducible into a vascular lumen surrounded by a vascular wall;means for unrolling the lining when the prosthesis is positioned withinsaid lumen so that the lining may engage the vascular wall to providesupport therefor, said means for unrolling including an inflatablechannel; filter means for filtering the blood which passes through theprosthesis when said lining is unrolled; and activation means connectedto said means for unrolling for causing said lining to unroll includingan elongate portion extendable outside of the body in which saidvascular lumen is located so that activation is achievable externally ofsaid body, said elongate portion being a hollow catheter detachablyconnected to said channel so that fluid may be introduced through saidcatheter to said channel to inflate same.
 15. The assembly of claim 14wherein said channel includes a filling port into which said catheter isdetachably connected, said filling port further including a one-wayvalve so that fluid introduced into said channel is prevented fromescaping upon detachment of said catheter.